Several cosmetic and medical treatments have been used in an attempt to treat sensitive skin and related conditions in general, and rosacea in particular. The skin disorder rosacea is of an unknown origin. It usually affects the middle third of the face causing skin redness, prominent vascularization, papules, pustules and swelling, as well as a predisposition to flushing and blushing. However, Rosacea can also occur on other parts of the body including the chest, neck, back, or scalp. The blood vessels near the skin dilate and become more visible there through, resulting in telangiectasia. The resulting papules and pustules resemble teenage acne, and are frequently mistaken for the same. Unlike acne, rosacea does not have blackheads or whiteheads. Rosacea, however, can occur in all age groups and in both sexes, where it tends to be more frequent in women but more severe in men.
The flushing and blushing regions of the face are affected by rosacea. Emotional factors such as anxiety, embarrassment, or stress may evoke or aggravate rosacea. In addition, a flare-up may be caused by environmental or climate variances, and UV exposure is known to aggravate rosacea. Furthermore, diet is also known to aggravate rosacea. Spicy foods, alcoholic beverages, hot beverages, and smoking are known to cause flare-ups.
Rosacea is not only an aesthetic complication. Rosacea is a chronic disease that has rarely been documented to reverse its progression. If untreated, the condition worsens and spreads. Untreated rosacea may cause a disfiguring nose condition called rhinophyma, which is characterized by a bulbous, red nose and inflamed cheeks. Severe rhinophyma may require surgery, an invasive procedure that may be avoided by timely treatment. Another problem of advanced rosacea is ocular. Persons afflicted with rosacea may experience conjunctivitis, a burning and grittiness of the eyes. If untreated, it may lead to serious complications such as rosacea keratitis, which damages the cornea and may impair vision.
Even though the exact origin of rosacea is unknown, several hypotheses have been offered. Many possible causes have been described as inducing the disease or contributing to its manifestation, including psychogenic, pharmacological, alimentary, thermal, infectious and immunological. It is also been claimed that Demodex mites may also cause the disease. Furthermore, the bacteria Helicobacter pylori, which is an important cause of gastritis and gastric and duodenal ulcers, has been reported as a possible cause for various dermatological disorders. The frequent association of rosacea with gastrointestinal tract disorders suggests a possible involvement of H. pylori in the cause of the skin disorder (Shiotani, A., Helicobacter, 6:60–65 (2001)).
As a result of the hypotheses as to the cause of rosacea, several treatments for the condition have been based thereon. Based upon the association of rosacea and H. pylori, antibiotics that are effective against H. pylori have also been used to successfully treat rosacea. Antibiotics, such as clarithromycin, tetracyclines, pantoprazole, and metronidazole, have proven to be effective in eliminating H. pylori, and in some cases rosacea (Mayr-Kanhauser, S. et al., European Journal of Gastroenterology & Hepatology, 13:1379–83 (2001)). In addition, combinations of antibiotics administered to patients having H. pylori and rosacea have proven to be effective in treating rosacea. The administration of a combination of amoxicillin, metronidazole, and bismuth subcitrate, to H. pylori positive patients has proven effective in decreasing the severity of rosacea, wherein the lesions were improved by the eradication of H. pylori (Utas, S. et al., Journal of the American Academy of Dermatology, 40:433–35 (1999)).
Metronidazole has demonstrated to be efficacious in treating rosacea. Twice-daily applications of the 0.75% metronidazole cream and a once-daily regimen of 1.0% metronidazole cream have found no significant difference in their effectiveness, but the once-daily regimen is best for patient compliance (Dahl, M. et al., Journal of the American Academy of Dermatology, 45:723–30 (2001)). However, it has also been noticed that patients treated with tetracycline and topical metronidazole, have had relapses in approximately twenty-five percent of cases in one case study (Thiboutot, D., Dermatologic Clinics, 18:63–71 (2000)). In addition, U.S. Pat. No. 5,849,776 to Czernielewski et al. teaches the effectiveness of Metronidazole, either individually or in combination with clindamycin, in the treatment of the papules and pustules of rosacea.
U.S. Pat. No. 5,972,993 to Ptchelinstev, assigned to Avon Products, Inc. ('993 patent), states that metronidazole has been shown to have an effect on papules and pustules of rosacea, but has been reported to be ineffective against skin redness, telangiectasia or flushing. Accordingly, the '993 patent teaches a composition having free radical scavengers, that is antioxidants, for the treatment of rosacea. Although the teachings may be effective against redness, telangiectasias, and flushing, the antioxidants do not address the papules and pustules caused by rosacea.
U.S. Pat. No. 6,126,947 to Savion et al. teaches a method for treatment of skin disorders, including rosacea, by topical application of an inhibitor of cholesterol synthesis. While inhibitors of cholesterol synthesis were previously administered orally or parenterally for lowering the cholesterol level of the patient they were never formulated as a topical composition. The extent of information available regarding its effectiveness in the treatment of the various aspects of rosacea is minimal and it only addresses the elimination of redness and not the effectiveness against the papules and pustules.
U.S. Pat. No. 6,284,802 to Bissett et al. ('802 patent) discloses the use of farnesol in a topical composition for the treatment of keratinous tissue. Although the '802 patent discusses rosacea as a possible skin disorder that may be treated by the farnesol composition, it does not provide any test results in support of the same.
U.S. Patent Application Pub. No. 2001/0034321 to Hebert discloses water-soluble salts of azelaic acid wherein the azelaic acid is combined with chitosan and administered to a subject. The Application fails to provide any concrete treatment of rosacea with the composition and merely mentions rosacea as a skin disorder that may be effectively treated by the taught composition.
An alternate study involving azelaic acid has shown that topical application thereof has beneficial effects in treating rosacea. Azelaic acid, a naturally occurring dicarboxylic acid, was first used in the treatment of acne and hyperpigmentation before being applied to rosacea. Topical application of azelaic acid has been shown to significantly reduce inflammatory papule lesions and erythema. However, the azelaic acid treatment did not produce any major improvement in telangiectasia. In addition, azelaic acid was not effective in treating pustules caused by rosacea (Bjerke, R. et al., Acta Derm Venereol, 79:456–59 (1999)).
Another study has reported the efficacy of metronidazole when compared with azelaic acid. Results of the treatments demonstrate that both medications are equally effective in reducing the number of inflammatory lesions and associated signs and symptoms of rosacea. However, the physicians administering the medications rated the global improvement of the patients more favorably for azelaic acid than metronidazole. It was determined that although both medications were effective in treating erythema, dryness, and burning associated with rosacea, both medications failed to effect telangiectasia. As a result, the study concluded that azelaic acid provides a very effective alternative to metronidazole cream even though neither compound is effective in addressing telangiectasia (Maddin, S., Journal of the American Academy of Dermatology, 40:961–65 (1999)).
Other current therapies for rosacea have had some drawbacks. Topically administered erythromycin and clindamycin, or similar antibiotics, are not tolerated for long term use because of the side effects associated therewith, such as gastrointestinal irritation. Topical corticosteroids have been effective in treating inflammation associated with rosacea, however long-term use thereof has resulted in skin atrophogenia. Isotretinoin has been shown to ameliorate rosacea and lasers can be used to treat telangiectasia. However, because of the chronic nature of rosacea, the ideal treatment needs to be used long-term in a safe and convenient manner.
Thus, a need exists for a composition and method for treating rosacea without causing the undesirable side effects of the prior art. In addition, a need exists for a composition and method for treating rosacea that is more effective. Furthermore, a need exists for a composition and method for stabilizing telangiectasia. The present invention satisfies these needs and provides related advantages as well.